Ken Clarke has staked his claim to lead the Conservatives, saying he is the only candidate who can win back the millions of lost voters to the party.

The former chancellor ended two weeks of speculation to announce he was standing for the job and immediately dismissed all his rivals - apart from Michael Portillo - as incapable of winning the next election.

However, he later told BBC2's Newsnight programme that he would very much like to have Mr Portillo in his shadow cabinet, describing the shadow chancellor as "the substantial figure" of the Tory Party.

Many people voted with a heavy heart for another term of Blair government because they could not see any electable alternative

Ken Clarke

At a news conference earlier in the day, he insisted he was best placed to stop the Tories dividing themselves over Europe and fight Labour on the economy and public services.

"The lesson from our crushing election defeat is clear to all of us - we must stop talking to ourselves about Europe and start talking to the electorate about the things that are important to them," he said.

Mr Clarke joins bookies' favourite Mr Portillo, Michael Ancram, David Davis and Iain Duncan Smith as a contender to replace William Hague, who stood down on 8 June.

'Humiliation'

Speaking to journalists at the Institute of Directors in London on Tuesday, Mr Clarke said the election had been "the most humiliating defeat the party had suffered in our entire history".

Warnings about a European superstate and loss of power to Brussels during the election campaign had been expressed in "vivid language", said Mr Clarke.

Clarke's pledges

Scrap opposition to Nice Treaty

Let shadow ministers campaign as they wish on euro

Offer shadow cabinet post to Michael Portillo

Focus on health and economy

"The electorate interpreted this as extreme English nationalism."

He said he would scrap his party's policy of opposing the Nice Treaty and the European rapid reaction force.

And he would allow shadow ministers to campaign and speak as they wished in any referendum on Britain's entry into the euro.

Mr Clarke said he would be glad to offer a place in the shadow cabinet to Mr Portillo - who he described as a "big figure" - but said he would not serve under his main rival if Mr Portillo won.

With 18 years government experience, including five cabinet posts on his CV, he said he was the candidate who could best develop new policies on public services.

Major figure

Mr Ancram, who as party chairman was largely responsible for the campaign so witheringly attacked by Mr Clarke, welcomed the former chancellor to the contest, saying he was a "major, significant figure".

But he suggested it was an irony that Mr Clarke should criticise the over-emphasis on Europe in the last election campaign, in a speech which heavily concentrated on just that issue.

Mr Davis - in Brussels on Tuesday to speak to MEPs - said he agreed that public services would be a key battleground for the Tories, but insisted that Mr Clarke was out of step with both the public and the party on Europe.

Popularity poll

A poll for bookmakers Ladbrokes suggests Mr Clarke - who held five cabinet posts under John Major and Margaret Thatcher - is the most popular choice of leader among voters.

Iain Duncan Smith announced new supporters on Tuesday

Bookmakers William Hill reacted to news of his announcement by slashing his odds from 7/1 to 2/1 making him second favourite behind Michael Portillo.

Despite Mr Clarke's wide popularity, he may struggle to win enough nominations from fellow MPs, who are largely eurosceptic, to make the final round.

The 166 Tory MPs will choose two candidates before a ballot of all 350,000 Conservative members.

This is Mr Clarke's second attempt to lead his party - he lost in the last round to William Hague in 1997 - and at the age of 60 will almost certainly be his last.

It takes his tally of declarations to 12, with supporters promising more to
follow over the coming week.

Meanwhile, nominations close for the chairmanship of the 1922 Committee of backbench Conservative MPs.

There are three contenders for the job which involves running the leadership contest - former Education Secretary Gillian Shephard, ex-Environment Minister Sir Michael Spicer and current 1922 vice-chairman John Butterfill.